When a gong is struck in the center, it’s lowest sound is heard. The vibration at this point is at the maximum. As the vibration travels to the outer rim it diminishes (see diagram below). The sound is higher at the outer rim. Often players, before striking a gong, tap the outer rim lightly to begin the vibrations. The vibrations of the gong are opposite to that of the bell, which has the maximum vibration at the rim.